Identification of the product formed by human erythrocyte galactosyltransferase.
Sepharose 4B-immobilized desialylated ovine submaxillary mucin was used as an acceptor for galactose transfer from UDP-galactose, catalyzed by a Triton X-100-solubilized galactosyltransferase from human erythrocyte ghosts. The product could be cleaved from the insoluble acceptor substrate by alkaline borohydride treatment and identified on Bio-Gel P-2 as a disaccharide. The nature of the glycosidic bond of the isolated material was elucidated by periodate oxidation/NaB[3H]4 reduction/acid hydrolysis and subsequent identification of the aminopolyol formed as L-threosaminitol. Specific cleavage of the enzymatic product by beta-galactosidase indicated a beta-configuration for incorporated galactose. These data permit classification of the enzyme as UDP-galactose: alpha-D-N-acetylgalactosaminyl-protein beta (1 leads to 3) transferase. Furthermore, in the presence of Triton X-100, the enzyme from normal erythrocytes catalyzed transfer of galactose to the glycan moieties of asialo-agalacto-glycophorin in Tn-erythrocytes from a patient with permanent mixed-field polyagglutinability.
D001212:Asialoglycoproteins; D002850:Chromatography, Gel; D004910:Erythrocyte Membrane / Q000201:enzymology*; D004912:Erythrocytes / Q000201:enzymology*; D005690:Galactose / Q000378:metabolism; D005700:Galactosyltransferases / Q000097:blood*; D006801:Humans; D008345:Manganese / Q000378:metabolism; D009077:Mucins / Q000378:metabolism; D017830:Octoxynol; D011092:Polyethylene Glycols; D014531:Uridine Diphosphate Galactose / Q000378:metabolism
D001212:Asialoglycoproteins; D009077:Mucins; D014531:Uridine Diphosphate Galactose; D011092:Polyethylene Glycols; D008345:Manganese; D017830:Octoxynol; D005700:Galactosyltransferases; D005690:Galactose